1. Field of the Invention
The invention generally relates to a light source device, in particular, to a light emitting unit.
2. Description of Related Art
Generally, a liquid crystal display, being a non-self-luminance display device, needs a backlight module providing uniform illumination. A light emitting diode (LED) is usually applied to, for example, a bottom type backlight module and an edge type backlight module, so as to achieve a backlight module being light, thin, and power saving. Currently, the bottom type backlight module has good light emitting uniformity and brilliance, thereby being usually used in various high order displays. In order to enable the light emission of the LEDs of a plurality of point light sources to be more uniform, usually a diffusion film layer is used to further diffuse the light beams emitted from the LEDs distributed in the backlight module, and a distance is maintained between the LEDs and the diffusion film layer for the diffusion of the light beams, that is, a so-called light cavity is formed. Alternatively, a secondary optical lens is utilized to further diffuse the light beams of the LEDs. However, when the light cavity is utilized to enable the light beams to be uniformly diffused, the volume of the backlight module may be excessively large, so that it is difficult to thin the display device. On the other hand, when the thickness of the light cavity is decreased, more LEDs are needed to be configured to prevent the backlight module from generating bright and dark fringes in which brightness and darkness exist at intervals. The configured secondary optical lens may increase the overall cost of the backlight module, and it is difficult to reduce the weight as well. Therefore, it is a problem still waited to be solved that how to compromise the light and thin volume, the light emitting uniformity, and the cost of the display device.
In ROC Patent Publication No. TWI265749, a backlight device is disclosed, tapered projections are formed on a position of a reflecting piece corresponding to an LED located thereabove, and the tapered projections may enable light beams directly emitted downwards by the LED to be guided along a transverse or horizontal direction. In ROC Patent Publication No. TWI360695, a bottom type backlight module is disclosed, a reflecting piece includes a plurality of first reflecting protrusions and a plurality of second reflecting protrusions, the first reflecting protrusions are located right under a line light source, and the first reflecting protrusions and the second reflecting protrusions are arranged at intervals and are in an elongated strip shape being parallel with one another. In ROC Patent Publication No. TW593926, it is disclosed that each reflecting unit of a reflecting plate further includes a protruding portion extending from a centre position of a middle face portion along a longitudinal direction of a corresponding line light source and protruding upwards. In ROC Patent Publication No. TW201007291, a backlight module is disclosed, a plurality of reflecting curved surfaces are formed on a bottom plate of a frame, light beam emitted from a spot light source towards the frame first reach the reflecting curved surfaces, are reflected by the reflecting curved surfaces to an optical plate above the spot light source for being emitted. In PRC Patent Publication No. CN201475729U, an LED light source beneficiating device is disclosed, two inclined planes being inclined outwards are disposed on a surface of a heat dissipation surface, the two inclined planes are symmetrically arranged as a V shape, and two LED modules having the same power are respectively assembled on the surfaces of the two inclined planes. In ROC Patent Publication No. TW526349, it is disclosed that protrusion shapes of a reflecting plate are continuous variations or discontinuous variations. In US Patent Publication No. US20050243578, it is disclosed that a curvature of a reflection surface of a reflecting piece is the same as that of a light conductive plate. In PRC Patent Publication No. CN101418929B, a widely uniform backlight device is disclosed. In PRC Patent Publication No. CN2729530Y, a shading plate having a non-transparent plate body provided with a reflecting surface is disclosed.